In this paper, a new technique of Electrocardiogram (ECG) denoising, is introduced and is based on Transformation Matrix for Non-Decimated Wavelet Transform (WT) and Wavelet/Total Variation (WATV) Denoising. It firstly consists of applying twice the Discrete Wavelet Transform (DWT) to the noisy ECG in order to obtain three wavelet coefficients which are the approximation coefficient, cA1 (at level 2) and two details coefficients, cD (at level 1) and cD1 (at level 2). Then, the two coefficients, cD and cD1 are denoised by applying the Transformation Matrix for Non-Decimated WT and we obtain two denoised coefficients, cDd and cDd1. The coefficient, cA1, is also denoised by applying the WATV Denoising and we obtain a third denoised coefficient, cAd1. Finally, the inverse of DWT is twice applied to the three denoised coefficients, cDd, cDd1and cAd1 in order to obtain the denoised ECG signal. The results obtained from the computations of SNR (Signal to Noise Ratio), PSNR (Peak SNR), MSE (Mean Square Error), MAE (Mean Absolute Error) and Cross-Correlation (CC), show the performance of this ECG denoising approach, proposed in this work.